Molecular and biochemical characterization of a distinct tyrosinase involved in melanin production from Aeromonas media.
A new tyrosinase was isolated from Aeromonas media strain WS and purified to homogeneity. The purified tyrosinase, termed TyrA, had a molecular mass of 58 kDa and an isoelectric point of 4.90. It exhibited optimal monophenol and diphenol oxidase activities under basic conditions (pH>8.0). TyrA had a relatively higher affinity to diphenol substrate L-dihydroxyphenylalanine (L-dopa) than many other tyrosinases. EDTA or glutathione notably inhibited the enzymatic activities of TyrA, whereas Triton X-100 and SDS activated them. The full-length TyrA gene was cloned, and it encodes a 518 amino acid protein with little similarities to other reported tyrosinases. However, the purified recombinant TyrA expressed in Escherichia coli demonstrated tyrosinase activity. These results suggest that TyrA is the first reported distinct tyrosinase involved in melanin production in the genus Aeromonas.
Wan
Xia
X
State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
Chai
Baozhong
B
Liao
Yi
Y
Su
Ying
Y
Ye
Tao
T
Shen
Ping
P
Chen
Xiangdong
X
D000333:Aeromonas / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D003001:Cloning, Molecular; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D007526:Isoelectric Point; D008543:Melanins / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D014442:Monophenol Monooxygenase / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment
D001426:Bacterial Proteins; D008543:Melanins; D014442:Monophenol Monooxygenase